This invention relates, in general, to continuously processing sheet materials. More particularly, it concerns itself with a portable photographic film processor capable of providing for the continuous processing of significant lengths of self-developing type film in a compact arrangement.
To date, the conventional processing of exposed cinematographic film is a rather elaborate, costly and time-consuming process. Besides, it requires that the exposed film be removed from the camera and then forwarded to a commercial developer for processing. After commercial developing, the processed film is returned by mail or otherwise to the user. Because of the need for commercial developing, several day or even weeks elapse ordinarily before the film can be viewed. Obviously, this is less than highly desirable, especially in situations wherein it is desirable to view the film immediately.
Recent motion picture systems have been devised in which exposure, processing and projection operations are carried out on a photographic film strip contained at all times in a multipurpose cassette. Such a system has been disclosed in several United States Patents, assigned in common with the present invention. In these cassettes, a supply of light-sensitive film is exposed in a camera adapted to receive the cassette. Processing or developing of the exposed film to provide the conventional series of positive transparent image frames is achieved by merely placing the cassette in a player or processor and viewing apparatus capable of activating a processor in the cassette. After processing, the player apparatus is operated as projector to advance the film, frame-by-frame, past a light source for viewing.
While the advance in the motion picture art represented by such an instant photographic system is apparant and needs no elaboration, such a system requires the use of a cassette which houses both the self-developable film strip and the processing station. In addition, a specially constructed camera for use with the cassette is needed, as well as a specially constructed processor and viewer.
It has been proposed recently to make the advantages of instant photography more versatile. More particularly, it has been proposed to use a self-developing or instant film of the transparency type in conventional cameras.
In this connection, the film would be exposed in and removed from a conventional camera and then processed in a separate processor for developing the latent images therein. As a result, fully developed transparencies would be produced. Commonly-assigned U.S. Pat. Nos. 4,145,133, 4,167,318 and 4,325,624 are representative of such an approach.
In processing film of the above type, it is critical for satisfactory developing that the processing fluid be applied to the film strip uniformly and with sufficient thickness within extremely small tolerances. Failure to achieve the above will result in undesirable developing which would diminish the quality of the image viewed during projection. It follows, therefore, that the achievement of a uniform layer of processing fluid on the film and a desired thickness thereof during the processing operation is a major focal point of attention in overall film development.
Beyond the need for achieving the above, there is a correspondingly important requirement that the imbibition of the film be carried out within a proper time interval. Imbibition process occurs when the emulsion side of the film strip is in contact with the processing fluid. Timing control of imbibition is particularly critical during the processing sequence. This is particularly true of certain film formats, such as color film which use the diffusion transfer process. Should the imbibition interval not be terminated at a proper point in time, the overall color balance may be improper. Likewise, in cases where the imbibition interval is shortened, beyond acceptable limits, the overall color balance will tend to be improper. Thus, it is critical not to have imbibition terminate prematurely or continue for an interval longer than that necessary. Thus, it can be appreciated readily that during the processing of the self-developing film of the above type, certain critical parameters requiring processing fluid application and film imbibition must be satisfied in order for the processing to produce high quality images. Moreover, these significant problems are further compounded if hundreds of feet of film are to be developed, especially if compact space considerations are desired.